Bach has made a name for herself by repeatedly taking retailers to court and winning cases after incorrectly being charging sales tax on items, sometimes for a matter of pennies.

She said consumers should take time to learn which frequently purchased items are exempt from the state’s sales tax to ensure they aren’t paying too much.

"Those pennies can quickly add up to many, many dollars," Bach said.

Sales tax adds 7 percent to the cost of a taxable item in Allegheny County, and 6 percent in other counties.

Most Pennsylvanians know the rules about food and clothing generally being exempt, but state law details hundreds of categories of items and identifies them as taxable or not taxable. State lawmakers ultimately approve the state’s sales tax rules.

For example, pet food is subject to sales tax while flea and tick shampoo for pets is not. Likewise, toilet tissue is not taxable but you will pay sales tax on a box of tissues.

Even though juice is food, it's either taxable or not taxable depending on the percentage of real fruit juice it contains. Twenty-five percent or greater real fruit juice is not taxable; other juices are subject to sales tax.

Yarn is either taxable or not taxable, depending on what the buyer plans to make with it. If the consumer plans to create a clothing item, state law requires that intended use of the yarn to be identified at the point of sale so the clerk will not charge sales tax. Yarn for other uses is taxable.

Bach says consumers who notice an error on a receipt should approach the store’s manager or customer service and ask for a refund.

"They certainly need to bring it to the attention of the manager because they then have the ability to change it in their system so that nobody else is overcharged,” Bach said.

Sales Tax Challenge Quiz

Sales Tax Challenge Quiz

Pittsburgh's Action News 4's Matt Belanger reviews the Pennsylvania regulations as to what is "Taxable" and what is "Not Taxable". Take our quiz to see how many items you guess correctly when going through the check-out line in the store.

Are Birthday Cakes subject to a Sales Tax? Click Next to check your answer...